DE4209832A1 - Shell catalyst, its production process and its use - Google Patents

Abstract

A catalyst contains 0.3 to 5, in particular 0.5 to 2 % by weight palladium on an activated carbon substrate, with respect to the dryed catalyst. The catalyst is obtained by impregnating the substrate with an aqueous palladium salt solution, by precipitating the palladium and by reduction (activation). In order to produce the catalyst, an alkaline-reaction activated carbon, having in particular a pH value of at least 8, is impregnated with the palladium salt solution and the excess fluid is separated after it has reached a pH value of at least 1, in particular at least 3 and preferably at least 4. A particularly high activity and long service life, as well as a particularly simple and economical production process, are thus obtained.

Description

The invention relates to a shell catalyst with 0.3 to 5, ins particular 0.5 to 2% by weight of palladium on an activated carbon support, based on the dried catalyst, obtainable by impregnation kidney of the carrier with an aqueous palladium salt solution, precipitates of palladium and reduction (activation).

The industrial hardening of unsaturated fats, oils and fat hydrogenation with nickel catalysts in the form of Fei NEN powders in intensively stirred autoclave under hydrogen pressures of up to 20 bar and temperatures of up to 250 ° C durchge leads. Especially when curing fatty acids occur special Pro open up. On the one hand, nickel silts form at these temperatures fen, which can only be removed by distillation from the product NEN. In addition, takes by the dissolution of nickel from the Kataly sator of its activity and thus its life from. The other is the separation of the catalyst from the product consuming and leads to  an increased product loss.

These disadvantages can be avoided by using palladium catalat used. Palladium is acid resistant. It is therefore formed no soaps that need to be separated. The lifetime of a sol Chen catalyst is then so high that an economically acceptable bare continuous curing in the stationary catalyst bed possible becomes. This eliminates the costly separation of the catalyst from the product.

Furthermore, such a catalyst is also excellent for the Hardening of food fats, as the cured product has no residual nickel content at all.

A catalyst of the type mentioned is known from Canadian Patent 11 57 844. As described in detail therein with citations from the patent literature, the preparation of a noble metal supported catalyst usually consists of the three steps of impregnation, precipitation and reduction. So z. For example, GB-B-7 99 871 zi animals, in which a carrier material PdCl ₂ solution impregnated and precipitated with NaHCO ₃ as Pd (OH) ₂ .

Similar processes are described in US 27 49 359, US 37 36 266 and DE 28 50 510 described.

In CA-B-11 57 844 is used to increase the activity of Palladiumkata lysators a catalyst carrier of extruded activated carbon first preloaded with water or an organic liquid before the Impregnation with the palladium salt solution takes place. He should be enough that the precious metal only in an outer shell the carrier is applied. After an impregnation time of 1 hour the pH is adjusted to one by adding sodium hydroxide solution  Value of about 4.0 set so that palladium as hydroxide falls. The preparation of the catalyst is carried out by filtration, Wa to complete drying and reduction.

The invention is based on the object, a catalyst of a of the type mentioned above with a considerably higher activity and height to create service life. In addition, a simpler and economic more economical method for producing such a catalyst to be provided.

This object is achieved in that alkaline reactive activated carbon, in particular with a pH of minde Stens 8, impregnated with the palladium salt solution and survive de liquid is separated after these have a pH of min at least 1, in particular at least 3 and preferably at least 4 er has enough.

Surprisingly, it has been shown that one is particularly ak tive catalysts with a very long service life, if the in the coal contained basicity sufficient, the pH of the precious metals tallsalzlösung after impregnation to a precipitate ausrei increasing minimum pH. In this case, the whole in the solution contained palladium in a peripheral region of the support precipitated. The supernatant solution is palladium-free, so that on an additional addition of an alkali, z. For example, sodium hydroxide solution, to Vervoll continuation of the precipitation can be dispensed with. You get a damage lenimprägnierung, wherein the noble metal concentration in a Randbe range of about 0.2 mm drops almost to 0, as does surface physics examinations showed.

As palladium salt z. As Alkalitetrahalogenopalladate, but also Palladium chloride, palladium nitrate or other palladium salts settable.  

The achievable in the hydrogenation with the catalyst according to the invention Jod numbers are significantly lower than when using the Catalyst described in Canadian Patent 11 57 844 when comparable hydrogenation conditions are present. So is after Example 10 of this patent with a liquid flow rate per Catalyst volume and time (LHSV) of only 0.2 l / h (2.5 l catalys and 0.625 l / h of palm kernel oil) at a pressure of 25 bar reached only an iodine value of 1.7. With the invention Catalyst is palm kernel oil at LHSV of about 1 / h against it Hydrogen iodide numbers below 0.6.

During the catalyst described in CA 1157844 in the test with Distilled tallow fatty acid only at very low fluid through set of 0.2 l / h iodine numbers less than 1 achieved and increasing the Load on 0.6 l / h, the iodine value already increases to 2.5 to 3.3 is it is possible with the catalyst according to the invention, under loads of 1 / h an iodine value of less than 0.5 and at loads of 2 to 3 / h still significantly less than 1 reach (Example 5).

Specific Paladium consumption is reported in CA 11 57 844 at 0.00089% specified. The corresponding value from example 5, after with 1 l Catalyst 2429 kg of fatty acids were cured, with activity has not yet noticeably decreased, is 0.00041% and is thus 50% below the reference value.

Particularly simple and economical, the invention can be Catalyst produce when the volume of saline solution about the same the total pore volume of the activated carbon. The impregnation can then by spraying the solution on the activated carbon carrier be guided.  

According to the invention, a pre-charge of the catalyst with liquid Not required before impregnation. Therefore, the active coal is preferably in a dry state in contact with the salt solution brought. Nevertheless, it forms as described in Example 2 this way a pronounced shell impregnation of the noble from metal.

It is also proposed that the activated carbon during the addition of Solution is moved.

In order to obtain a low-halide catalyst should also according to impregnating with palladium halide salts, the product obtained filtered off and washed with water.

The invention also relates to a method for producing this Ka talysators and a process for hardening fats, oils, grease acid esters, other fatty acid derivatives and in particular free Fatty acids by catalytic hydrogenation with hydrogen. The herd tion is preferably at temperatures of 80 to 250 ° C and Abso Lute pressures of 0.5 to 50 bar performed. The curing can be chosen be carried out so that the iodine number after the reaction possible As low as it usually is in the hardening of fatty acids is required for technical applications, but also in the Här tion of methyl esters (Example 8, 18) or neutral oils (Example 15) may be desirable. These reactions are usually carried out at 20 bar hydrogen pressure. It is also possible highly iodine-based starting materials under defined conditions to harden certain iodine numbers to certain application-related To achieve properties. It must then from the Normalbedingun deviating parameters (pressure, temperature) can be set. This so-called partial cure is described in Example 12 for the Här tion of rapeseed oil fatty acid and Example 16 for the curing of suns flower oil and rapeseed oil.  

In particular, it is proposed in the curing of fatty acids that one uses distilled fatty acids, as their color in the cure is so much improved that the salable for salable products manoeuvrable color is achieved without the usual after-treatment tion must be carried out by adsorption.

Embodiments and test results of the invention will be described below, inter alia, with reference to drawings.

Show it

Fig. 1, the palladium distribution over the layer thickness of a catalyst OF INVENTION to the invention,

Fig. 2 shows the results of a life test in a diagram in which the residual iodine, the liquid loading (LHSV), the temperature Tempe and the acid value are plotted against the overall throughput and

Fig. 3 is a flow chart of a pilot plant for a continuous fatty acid curing.

Examples example 1 Preparation of the catalyst

A suspension of 3.322 g of PdCl ₂ in 160 ml of water was added 2 ml of HCl (conc) and 2.21 g of NaCl and stirred until a clear solution resulted. This solution was added at room temperature with shaking to 100 g of activated charcoal (Cecarbon GAC 30, sieve fraction greater than 1.4 mm) in a 500 ml flask. The activated carbon had a surface area of 1140 m ² / g by BET, a pore volume of 0.32 ml / g, measured by Hg porosimetry, pH of 8.3 (10% in water) and an ignition residue of 13.4 %. The solution spontaneously decolorized and the pH of the supernatant increased from below 1 to about 3. The reaction was allowed to stand for 1 h with the pH rising to 4 to 5. Subsequently, the supernatant solution was filtered off and washed with almost 2 l of water until free of chloride. The catalyst was sucked dry and dried overnight at 120 ° C. Yield: 96.2 g (dry).

Example 2 Preparation of the catalyst

In a ploughshare mixer at room temperature 1680 g of a solution of Na ₂ PdCl ₄ (Pd content of 20 g) in a running mixer to 1000 g of the same activated carbon granules Cecarbon GAC 30 as in Example 1 were given. After a short life, the granules were rinsed with a little water from the mixer and reacted in the beaker for 1 h after. The catalyst was armor washed twice with 10 l of water, sucked dry and dried at 120 ° C. Yield: 1051.5 g.

Precious metal distribution

In the case of the catalyst according to Example 2, the distribution of palladium within one grain was determined by means of energy-dispersive X-ray microanalysis. The results are shown in FIG . The palladium concentration at the particle surface was arbitrarily set to 1 and the concentration within the catalyst grain was determined relative thereto. It can be clearly seen that the palladium concentration has dropped within a distance of 200 microns from the surface to 10%.

Example 3 Preparation of the catalyst

In a paddle mixer with a total volume of about 20 l was allowed with the mixer running to 5000 g activated carbon granules Cecarbon GAC 30 (sieve fraction 1.2 to 3.0 mm) at room temperature 3595 g Pd-solu tion (Na ₂ PdCl ₄ , 100 g Pd ) and 1400 g of dist. To run water. Then the mixer was stopped, the contents drained, with 2 liters of dist. Rinsed with water and 1 l H ₂ O was added so that the coal was covered with liquid. After 1 hour, was filtered with suction through a suction filter. This gave 6.5 l of filtrate with a pH of 4.5. At closing was washed five times with 10 liters of water, so that the filtrate contained only small amounts of chloride ions. The Kata analyzer was dried at 120 ° C. In the same way, two more batches were prepared, so that a total of 15 kg of catalyst with a total volume of about 30 l was available.

activation

For activation prior to use, all catalysts prepared in the examples were reduced. In a stream of nitrogen of 1 Nm ³ / h was heated to 200 ° C within 4 h. Then 50 Nl / h of hydrogen were added to the nitrogen for 20 h at 200 ° C. At closing the temperature was kept for 2 h in pure Wasserstoffatmos phere before the catalyst was used for curing.

Example 4 Use of the catalyst from Example 1

The catalyst prepared according to Example 1 was in a laboratory hardening apparatus tested. A shaft reactor with a catalyst volume of 150 ml (catalyst charge 66.6 g) was in the same stream with liquid and gaseous phase acted upon. All Versu che took place at a hydrogen pressure of 20 bar. As raw material For hardening, distilled and crude tallow fatty acid were added puts. Throughput, LHSV and temperature T were in wide range varies. Individual results are listed in Tab. 1. It will it is clear that the catalyst is very strong even at low temperatures is active (150 ° C, LHSV = 1, iodine value JZ = 0.46) and at high temperature can be heavily loaded (200 ° C, LHSV = 3,2, JZ = 0.75). Under all conditions the catalyst is highly selective, i. H. There are no unwanted side reactions taking place would make noticeable by a decrease in the acid number SZ.  

Table 1

curing results

Example 5 Use of the catalyst from Example 2

The catalyst prepared according to Example 2 was a service life subjected to a test. To this was added 500 g corresponding to 1 liter of the catalyst in a pilot plant over a period of 116 days various fatty acids, mainly distilled tallow fatty acid tested under hydrogenating conditions (hydrogen pressure 20 bar).  

Throughput and temperature were varied within wide limits. It was found that even after this long time and a quantity of raw material corresponding to 4858 kg of product / kg of catalyst, the activity of the catalyst had not appreciably decreased (JZ less than 0.5 at LHSV = 1 and a temperature of 190 ° C). Results over the entire experimental period are shown graphically in FIG . Iodine number and LHSV or temperature and acid number are each read on the same scale. The increase in iodine number on the left in the diagram is due to the use of crude fatty acid.

Example 6 Use of the catalyst from Example 3

With 13.2 kg of the catalyst prepared according to Example 3 curing experiments were carried out on a pilot scale. It is a circulating gas system in which the excess of hydrogen is separated from the product and recirculated ( FIG. 3).

Fatty acid 1 is pumped via a template 2 and a heater 3 together with the recycle gas in a reactor 4 . The separated in Hochdruckab separator 5 cured product collects in a pre-position. 6 From the cycle gas compressor 7 , the excess hydrogen and fresh hydrogen 8 is returned to the heater 3 .

The test parameters are listed in Tab.

experimental parameters Reactor type: Single tube Diameter: 63 mm Length of catabet: 8000 mm Volume Katabett: 25 l L / D: 127: 1 Print: 20 bar Cycle gas flow rate: 1.4-1.8 Nm³ / l cat * h throughput: 1 m³ / m³ cat * h Liquid loading: 8 m³ / m² * h Gas load (190 ° C): 950-1220 m³ / m² * h

Different fatty acid qualities were tested, in particular in terms of the color of the products. The mean values of the results Details for the individual products are summarized in Tab. 3 and 4 summarizes. In particular, from Table 4 it is clear that the color of Products significantly improved by the curing step.  

Table 4

Color codes (Lovibond 5 1/4 '')

example 7 Preparation of the catalyst

716.2 g of activated carbon extrudate (Carbotech A35 / 2, 2 mm extrudate, BET surface area 890 m ² / g, Hg pore volume 0.74 ml / g, pH 8.7 (10% in H ₂ O) were added Room temperature with 514.7 g of Pd salt solution (14.32 g of Pd as Na ₂ PdCl ₄ ) and 200 g of H ₂ O. Subsequently, 1000 g of water were added and after one hour was filtered through a Saugfil ternutsche and with 17 l The mixture was then dried at low temperature, and then dried overnight at 120 ° C. Yield 717.5 g.

Example 8 Use of the catalyst from Example 7

355 g (corresponding to 1 l) of the catalyst from Example 7 were in a hydrogenation apparatus over a period of 18 operating days with various raw materials tested for activity. After the usual, Activation described above was the catalyst with 171 l of tallow methyl ester (Me-Ti, JZ = 50.2, SZ = 0.80, VZ = 199.5) and 218 l of tallow fat acid (Ti-FS, JZ = 58.5, SZ = 206.3) applied. It was followed by DE Hardening results achieved:

example 9 Preparation of the catalyst

1000 g of active carbon granules CECARBON GAC 616G of grain size 1.2-3.4 mm and a bulk density of 0.51 kg / l (pH 7.8, BET surface area of 1190 m ² / g and Hg pore volume of 0 , 15 ml / g) were submitted in Mischbehäl ter.

718.9 g of solution of Na ₂ PdCl ₄ (corresponding to 20.0 g of palladium) were combined with 281 g of H ₂ O and added to the charcoal carrier in the manner described. It was then diluted with 667 g of H ₂ O to adjust the same liquid ratios. After 1 h life was filtered as usual and washed out with low chloride.

The pH of the primary filtrate was 3.5. At the end of the rinse procedure the wash water had a pH of 5.5. The moist granules was dried at 120 ° C.

Example 10 Use of the catalyst from Example 9

520 g (corresponding to 1000 ml) of the Ka prepared according to Example 9 talysators were used in a 1.2 l hydrogenation plant over a period of time of 36 operating days with a total of 660 l of raw materials Type (Bovine feeding talc: JZ 46.6, SZ = 2.70, VZ = 195, bone fatty acid: JZ = 60.6; SZ = 205.7; Tallow fatty acid: JZ = 58.5, SZ = 206.3; Talgmethyl ester: JZ = 48.9, SZ = 0.40, VZ = 195).

The following curing results were achieved:

example 11 Preparation of the catalyst (1% Pd / C)

1500 g of active carbon granules CECARBON GAC 30 of particle size 1.3-3 mm and a bulk density of 0.49 kg / l (pH 8.3 (10% in H ₂ O); BET surface area of 1140 m ² / g and Hg pore volume of 0.32 ml / g) were placed in the mixing vessel and with a solution of 539.2 g of Na ₂ PdCl ₄ (corresponding to 15.0 g of palladium) in 961 g of H ₂ O, ie 1500 g solution, mixed quickly with stirring. Subsequently, 1000 g of H ₂ O was added to reach a supernatant liquid level. After 1 h of service life, the impregnated supported catalyst was filtered off from the brine. With 30 l of washing water, the catalyst was rinsed with low chloride, then dried at 120 ° C and used for Härtungsver searches.

Example 12 Use of the catalyst from example 11

495 g corresponding to 1000 ml of the catalyst prepared in Example 11 sators were in a hydrogenation apparatus over a period of 51 Operating days with a total of 1500 l different raw materials beauf beat:

In the curing of rapeseed oil was at different pressures and temperatures hardened to specifically enter certain iodine numbers put. For the other raw materials, the hydrogen pressure was like usually kept constant at 20 bar.

The following curing results were achieved:

Example 13 Preparation of the catalyst (0.5% Pd / C)

1500 g of active carbon granules GAC 30 with a grain size of 1.3-3 mm (bulk density 0.49 kg / l, pH 8.3, BET surface area 1140 m ² / g and Hg po ren volume 0.32 ml / g) were presented in the mixing vessel.

269.6 g of Pd salt solution as Na ₂ PdCl ₄ (corresponding to 7.5 g of Pd) were combined with 1230 g of H ₂ O and mixed with the carbon granules. With 1000 g of H ₂ O was rinsed. As in Example 11 was rinsed low in chloride and dried at 120 ° C, the moist catalyst granules.

Example 14 Use of the catalyst from Example 13

525 g corresponding to 1000 ml of the catalyst prepared in Example 13 sators were used in a hydrogenation apparatus over a period of 17 Operating days with a total of 369 l of raw materials acted upon. To Roh substances were used:

The following curing results were achieved:

example 15 Preparation of the catalyst

1500 g of active carbon granules (GAC 30 of grain size 1.2-3.4 mm, bulk density 0.51, pH 7.8, BET surface area 1190 m ² / g and Hg po renvolumen 0.15 ml / g ) were presented in the mixing vessel.

1078.4 g of Pd salt solution as Na ₂ PdCl ₄ (corresponding to 30.0 g of palladium) were combined with 421.6 g of H ₂ O and added to the carbon granules submitted. Then, 1000 g of H ₂ O were added and the product he kept aufgear after life in the manner described above aufgear.

The first filtrate had a pH of 2.8, the last washing water 4.2.

Example 16 Härtungsversuche

527 g of the catalyst prepared according to Example 15 (corresponding 1000 ml) were dissolved in a hydrogenation apparatus over a period of 55 operating days loaded with 1172 l of different raw materials, namely:

First, the three triglycerides were used. There were suns flower oil and rapeseed oil only selectively hardened, d. H. the iodine number became lowered to a certain mean value. All attempts will be carried out at 20 bar hydrogen pressure. The following results were achieved:

example 17 Preparation of the catalyst (2% Pd / C)

716.2 g of activated carbon (2 mm extrudate Carbotech A35 / 2 with a bulk density of 0.36 kg / l, a BET surface area of 892 mm ² / g and a Hg pore volume of 0.74 ml / g ) were placed in a mixing container pre and mixed with 514.7 g of solution of Na ₂ PdCl ₄ (corresponding to 14.3 g Palla dium) and 200 g of H ₂ O with stirring.

Subsequently, it was mixed with 1000 g of H ₂ O and filtered after 1 h of standing time in the manner described above. The first filtrate had a pH of 1.6, which was 3.05 at the end of the washout. The low-chloride, moist catalyst was dried at 120 ° C and used for activity determination in a hydrogenation plant.

Example 18 Use of the catalyst from Example 17

355 g (corresponding to 1000 ml) of the prepared according to Example 17 Catalysts were in a 1-liter hydrogenation apparatus over a Be operating period of 18 days with a total of 389 l of raw material, namely with

The following results were achieved:

LIST OF REFERENCE NUMBERS

1 fatty acid
2 template
3 heaters
4 reactor
5 high pressure separator
6 template
7 circular gas compressor
8 fresh hydrogen

Claims (14)

1. coated catalyst with 0.3 to 5, in particular 0.5 to 2 wt .-% palladium on an activated carbon support, based on the dried th catalyst, obtainable by impregnating the support with an aqueous palladium salt solution, precipitation of palladium and reduction, characterized in that alkaline-reacting activated carbon, in particular having a pH of at least 8, is impregnated with the palladium salt solution and the supernatant liquid is separated off after it has reached a pH of at least 1, in particular at least 3 and preferably at least 4. 2. coated catalyst according to one of claim 1, characterized, that the volume of saline solution is approximately equal to the total pore volume the activated carbon. 3. coated catalyst according to one of claim 1 or 2, characterized, that the activated carbon in a dry state with the salt solution in Contact is brought. 4. coated catalyst according to one of claims 1 to 3, characterized, that the activated carbon moves during the addition of the salt solution becomes. 5. coated catalyst according to one of claims 1 to 4, characterized,  that after impregnation with palladium halide salts he filtered product is filtered off and washed with water. 6. A process for the preparation of a shell catalyst with 0.3 to 5, in particular 0.5 to 2 wt .-% palladium on an activated carbon carrier, based on the dried catalyst, wherein the Support impregnated with an aqueous palladium salt solution, Pal ladium fails and reduces, characterized, that an alkaline-reacting activated carbon, in particular with a pH of at least 8, with the palladium salt solution in the impregnates and separates the supernatant fluid after this has a pH of at least 1, in particular at least 3 and preferably has reached at least 4. 7. The method according to claim 6, characterized, that the volume of saline solution is approximately equal to the total pore volume the activated carbon. 8. The method according to claim 6 or 7, characterized, that the activated carbon in a dry state with the salt solution brings in contact. 9. The method according to any one of claims 6 to 8, characterized, that the activated carbon is moved during the addition of the salt solution. 10. The method according to any one of claims 6 to 9, characterized, that is filtered off after impregnation, the product obtained and washes with water.   11. Process for curing unsaturated fats, oils, fatty acid esters, other fatty acid derivatives, in particular free fatty acid by catalytic hydrogenation with hydrogen using A catalyst according to any one of claims 1 to 5. 12. The method according to claim 11, characterized, that the curing at temperatures of 80 to 250 ° C and absolute Press from 0.5 to 50 bar is performed. 13. The method according to claim 11 or 12, characterized, that one uses distilled fatty acids. 14. The method according to any one of claims 11 to 13, characterized, that oils and fats, fatty acid esters and other fatty acid derivatives vate selectively hydrogenated to a given iodine value to feed fatty, fatty acid esters and other fatty acid derivatives with desired obtain melting properties.